Heartbeat of Nanoparticles Made Visible

But, even the best microscopes can not resolve these nanoparticles, which are therefore very difficult to study. Now assistant professor Markus Lippitz from the Max Planck Institute for Solid State Research, together with Thorsten Schumacher achieved a breakthrough. He used a nano-antenna, which has already been applied successfully as a nanosensor by Professor Harald Giessen from the 4 . Physics Institute of the University of Stuttgart.

Lippitz' dream is to investigate the mechanical properties of the smallest nanoparticles. "The surface to volume ratio would then be huge, and we would expect new nanomechanical properties," he explains. To get one step closer to this dream, he placed a small antenna near the tiny particle.

This nano-antenna focuses the laser light very tightly on the nanoparticle under examination. Consequently, the light modulation due to the nanomechanical vibrations are very efficiently coupled back into the laser beam. “This is the first time that someone uses nano-antennas to investigate ultrafast nonlinear optical effects. The whole thing works like a mobile phone, in which the antenna makes that the electromagnetic waves are effectively coupled into the small electronic circuits of the phone“ Lippitz explains.

Lippitz sees a huge potential for his new method: "In the future, we will be able to put the smallest nano-objects of a few nanometers in diameter in the focal point of a nano-antenna and study them using non-linear optical processes of only a few femtoseconds duration (1 femtosecond = 1 billionth of a millionth of a second take). Then we can make movies on the nanoscale, using the most extreme slow motion. Not only can we investigate nanoobjects such as semiconductor quantum dots, but also chemical and biological objects, such as molecules and viruses."